1. Field of the Invention
The present invention relates to systems and methods for controlling spacecraft payloads, and in particular to a method and apparatus for controlling a spacecraft gimballed payload.
2. Description of the Related Art
Spacecraft such as satellites often include payloads such as antennas and sensors. Often, such payloads are disposed on gimballed platforms, which help isolate the payload from spacecraft motion, and allow the payload to be pointed to space or terrestrially-based targets as desired.
Target acquisition control is a procedure wherein the gimballed platform is oriented so that the payload is directed to point sufficiently close to the inertial payload-target line of sight (LOS) angle to permit acquisition and subsequent tracking of the target, either by the payload itself or by an acquisition and/or tracking sensor accompanying the payload and typically mounted on the gimbal. Examples of gimballed payloads include RF crosslink antennas for communicating with other spacecraft and optical laser devices. Examples of acquisition sensors include autotrack receivers, beacon trackers, and optical devices.
Acquisition control can be a challenging task, particularly when the spacecraft and/or the target are in motion. It is also important that the time to acquire and track the target (the acquisition time) be minimized. In commercial communications systems, acquisition time is “down time” in the sense that the payload cannot perform its mission until the target is acquired, and longer acquisition times mean shorter service times. For defense applications, the acquisition time is even more critical, as excessive acquisition times can result in mission failure.
What is needed is a system and method for increasing target acquisition probabilities while minimizing acquisition time. The present invention satisfies that need.